1. Field of the Invention
This invention relates to a process for producing hexafluoroacetone or its hydrate, and more particularly to a process for producing hexafluoroacetone or its hydrate with effective utilization of octafluoroisobutene or its adduct with alcohol etc.
2. Description of the Prior Art
Hexafluroacetone is a monomer for producing a synthetic resin, a synthetic rubber, etc., or is used as an intermediate for crosslinking agents such as bisphenol AF, etc., or as an intermediate raw material for medicaments, agricultural chemicals, etc.
The following processes have been so far proposed for producing hexafluoroacetone or its hydrate having the said applications. ##STR1##
However, the foregoing processes have the following disadvantages.
(1) Oxidation reaction by potassium permanganate proceeds vigorously and the by-produced manganese dioxide is an industrial waste which is hard to treat. PA1 (2) High purity oxide is hard to synthesize from hexafluoropropene and thus the produced hexafluoroacetone contains hexafluoropropene, etc. PA1 (3) In the oxidation of hexafluorothioacetone dimer by nitric acid, the produced hexafluoroacetone hydrate contains NO.sub.2 and SO.sub.2, whose removed is troublesome. PA1 (4) In the use of hexachloroacetone, chlorine not only contributes to increase the weight, but also is synthetically not efficient, and furthermore toxic antimony pentachloride is required. Thus, a high purity product is hard to obtain. PA1 (1) a process for oxidizing a heptafluoroisobutenyl alkyl, aryl or benzyl ether with ozone, PA1 (2) a process for thermally decomposing an octafluoroisobutyl lower alkyl, phenyl or benzyl ether at a temperature of 50.degree. to 600.degree. C. in the presence of oxygen and an activated carbon catalyst, and PA1 (3) a process for thermally decomposing a heptafluoroisobutenyl lower alkyl, phenyl or benzyl ether at a temperature of 50.degree. to 600.degree. C. in the presence of oxygen and an activated carbon catalyst.
Besides the foregoing prior art, a process for producing hexafluoroacetone or its hydrate by reaction of heptafluoroisobutenyl alkyl ether with oxygen under light irradiation has been proposed by the present Applicant [Japanese Patent Application Kokai (Laid-open) No. 61-277,645], but the yield on the basis of raw material heptafluoroisobutenyl alkyl ether is as low level as 19.2 to 19.4%.